Project 2: The Plasminogen ?Interactome? following Injury ABSTRACT: With improved care most mortality after major trauma now occurs early (<12 hrs). Our hypothesis from Project Alpha, implicates Trauma-induced coagulopathy (TIC), specifically dysregulated clot stability with either too much or too little fibrinolysis, which can change quickly). Decades of research on blood clotting disorders point to plasmin as the chief regulator of clot breakdown. Recent advances in the ability to analyze the hundreds of proteins changing rapidly in patient blood, leads us to conclude that some of these may be playing roles that have not been previously suspected. We hypothesize that blood loss or replacement (transfusion) versus cell lysis releases proteins that try to ontologically correct clotting by activating or deactivating plasmin. In Specific aim1, we correlate which proteins (both known and unknown) predispose towards enhanced or diminished plasmin activity and thereby clot stability, paying particular attention to proteins that were introduced during transfusion. In Specific aim 2, we concentrate on three classes of proteins that might interact with plasmin, due to their structure, but that are, typically, not present in abundance in normal blood, nor known to regulate plasmin and clot stability. Focusing on those protein structures containing lysines which bind to kringle domains, actin binding domains, and collagen binding domains, we verify their ability to activate or inhibit clot stability as predicted in Aim 1. These laboratory studies will assess the ability of these candidate proteins to physically bind and influence plasmin, directly or indirectly, by interfering with associated activators and inhibitors. Lastly, in Specific aim 3, we utilize the fact that certain non-trauma surgical patients show aspects of defective clot stability similar to the states of fibrinolysis in injured patients. These include a. patients who require liver transplantation, who demonstrate weak clot stability and hyperfibrinolysis, b. obese patients undergoing bariatric surgery, who are at risk for developing unwanted venous clots with fibrinolytic shutdown, and c. end- stage renal disease (ESRD) patients, who demonstrate clots that are slow to form but not easily dissolved with physiologic fibrinolysis. While these conditions are attributed to higher or lower levels of known plasmin mediators, or even enhanced platelet-fibrin interactions, the roles of new proteins, that we have discovered as capable of modulating plasmin regulated clot stability, has not been investigated. Impact: This proposal will reveal novel mechanisms of plasmin dysregulation, which can be examined more closely by Project 1 in trauma patients. These results are also likely to improve personalized resuscitation with blood products in the near future. Therapies based on the regulation of plasmin by these unique proteins may impact survival from blunt and penetrating injuries as well as for other surgical patients with coagulopathies.